(a) Field of the Invention
The present invention relates to a material for dentistry in which a specific (meth)acrylate compound is blended.
(b) Description of the Related Prior Art
In recent years, many materials for dentistry comprising synthetic polymers have been developed, and some of them take the form of compositions each comprising monomers, a polymerization initiator and other components which can be polymerized and cured when used. Examples of such compositions include (1) crown restoration materials such as chemically polymerizable and photopolymerizable composite resins and quick-curing resins (fast-polymerizable resins), (2) adhesive and transitory adhesives, for example, between a composite resin and a tooth, between a metal and a tooth, and between teeth, (3) chemically polymerizable and photopolymerizable pit and fissure sealants, (4) artificial crown materials such as thermally polymerizable and photopolymerizable hard crown resins, (5) transitory crown materials such as polycarbonate crowns and fast-setting resins for crowns, (6) denture plate materials such as thermally polymerizable, cold polymerizable (inclusive of casting type) and injection-moldable acrylic resins and adhesive denture plate reins, (7) restoration materials such as denture plate lining agents and restoration fast-setting resins, and (8) impression materials such as agar, alginates, polysulfide rubbers, silicone rubbers and (meth)acrylic impression materials.
Among these materials, for example, as the composite resin or the hard crown resin, there is used a blend of at least one monofunctional monomer, at least one polyfunctional monomer, an inorganic filler and a radical polymerization initiator, and as the crown resin, the sealant or the adhesive, there is used a combination of at least one monofunctional monomer, at least one polyfunctional monomer and a radical polymerization initiator. Furthermore, a restoration material such as the denture plate, the denture plate lining agent and the restoring quick polymerizable resin is required to be colorless and transparent, to be easily colored, to be aesthetic and to be excellent in workability, and therefore as this kind of restoration material, there is used a mixture of a polymer component (which is in the state of a powder in most cases) such as polymethyl methacrylate (hereinafter referred to as "PMMA") and polyethyl methacrylate (hereinafter referred to as "PEMA"), at least one monofunctional monomer, at least one polyfunctional monomer and a radical polymerization initiator.
Examples of the above-mentioned monofunctional monomer component include methyl methacrylate (MMA), ethyl methacrylate (EMA), butyl methacrylate (BMA), 2-hydroxyethyl methacrylate (HEMA) and H.sub.2 C.dbd.C(CH.sub.3)COOC.sub.2 H.sub.4 OCOC.sub.2 H.sub.5. Examples of the polyfunctional monomer component include 1,6-hexanediol dimethacrylate (HD), ethylene glycol dimethacrylate (1G), triethylene glycol dimethacrylate (3G), bisphenol A diglycidyl dimethacrylate (Bis-GMA), trimethylolpropane trimethacrylate (TMPT) and dipentaerythritol pentaacrylate (2P5A).
In addition, in Japanese Laid-open Patent Publication No. 1987-178502, a material for dentistry is described which contains, as the main component, a diester compound represented by CH.sub.2 .dbd.CR.sub.1 COOR.sub.2 OCOR.sub.3 (wherein R.sub.1 is a hydrogen atom or an alkyl group, R.sub.2 is an alkylene group and R.sub.3 is an alkyl group).
However, the composite resin, the hard crown resin, the quick-curing crown resin, the sealant and the adhesive are required to be (1) free from a strong foul odor, since they are directly put in a mouth. Furthermore, they are required to be free from irritation to a skin and a mucous membrane, since they are often brought into contact with dental pulp in pits of teeth. In addition, they must maintain strength under circumstances in a mouth, since they remain in the mouth for a long period of time after curing, and from this viewpoint, (3) polymers having high water absorption properties are inconvenient.
Moreover, the restoration materials such as the denture plate and the denture plate lining agent are required to be (1) free from a strong foul odor and (2) free from irritation to a skin and a mucous membrane, since they are manipulated by hands of a dentist or a dental technician, or since they are directly brought into contact with an oral mucous membrane for the sake of molding.
However, the above-mentioned monomers inconveniently cannot meet all of these requirements (1) to (3).
For example, monomers such as MMA, EMA, BMA, HEMA, HD, 1G, 3G, TMPT and 2P5A cannot meet the above-mentioned requirements (1) and (2), and monomers such as H.sub.2 C.dbd.C(CH.sub.3)COOC.sub.2 H.sub.4 OCOC.sub.2 H.sub.5 and Bis-GMA cannot meet the above-mentioned requirements (3). Even if these monomers are combined, all of the aforesaid requirements cannot be satisfied. Therefore, the development of a composition by which these problems are solved is desired.
The diester compounds described in the above Japanese Laid-open Patent Publication No. 1987-178502 are excellent in point of less stimulation, but they have perceptibly high water absorption properties. In consequence, their strength tends to deteriorate when they are used as dental materials, and what is worse, they are liable to color.
In the case of the above restoration material, a monomer component is mixed with a polymer component at a suitable ratio, and the mixture is then placed in a predetermined mold or put in a mouth for the sake of molding. Afterward, the material is taken out therefrom, and then polymerized at room temperature or under heating, thereby obtaining the restoration material. However, in the course of this molding, it is important that the material takes the state of the so-called dough stage for a suitable period of time. In short, the composition which is free from a strong foul odor and less irritant and which has a suitable period for dough stage is demanded.